1. Field of the Invention
The present invention relates to a method for manufacturing an optical memory element which optically records the information therein.
2. Description of the Prior Art
Recently, an optical memory system has been developed, which optically stores the information in high density and in the mass storage order. The optical memory system ensures the high density, mass storage because the information recording unit (bit) is determined by the diameter of the beam which is used in the recording operation and the reading operation. Generally, the bit size is selected about 1 .mu.m.
However, in order to ensure the high density, mass storage, the optical beam position must be accurately controlled so that the information is recorded at a predetermined position, and the information is read out from a preselected position. In the case of the optical memory system of the read only type, address information can be recorded on the optical memory element when data information is recorded on the optical memory element. Accordingly, the optical beam position is controllable while the data information is read out from the optical memory element. However, in the optical memory system of the add-on-memory type or the erasable memory type, it is difficult to record the address information on the optical memory element while the data information is recorded on the optical memory element. Therefore, in the add-on optical memory or the erasable optical memory, guide signals or guide addresses are normally recorded on the optical memory element, which are used to control the optical beam position.
FIG. 1 schematically shows the general construction of the optical memory element of the add-on-memory type or the erasable memory type. Stripe-shaped grooves are formed on the optical memory element. The information recording operation and the information playback operation are conducted along the stripe-shaped grooves. The stripe-shaped grooves can be intermittently formed so as to bear the bit information representing the address of the groove. Some methods for forming the stripe-shaped grooves on the optical memory element have been proposed.
FIG. 2 shows an example of the conventional method for forming the stripe-shaped grooves on the optical memory element. A nickel (Ni) stamper 1 having the stripe-shaped grooves formed thereon is employed to transcribe the stripe-shaped grooves onto a resin substrate 2 made of, for example, acrylic or polycarbonate, through the use of the injection molding method.
FIG. 3 shows another example of the conventional method for forming the stripe-shaped grooves on the optical memory element. Photo-polymer 3 is interposed between the stamper 1, having the stripe-shaped grooves formed thereon, and a substrate 4 made of, for example, glass or acrylic so as to transcribe the stripe-shaped grooves onto the photo-polymer 3 (namely, the 2P method).
Both methods employ the resin layer in the optical memory element. Therefore, there is a possibility that oxygen or moisture reaches the recording material through the resin layer. This will deteriorate the recording material. That is, the conventional method does not ensure a stable operation of the optical memory element.